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BackgroundErgopeptines are a predominant class of ergot alkaloids produced by tall fescue grass endophyte Neotyphodium coenophialum or cereal pathogen Claviceps purpurea. The vasoconstrictive activity of ergopeptines makes them toxic for mammals, and they can be a problem in animal husbandry.ResultsWe isolated an ergopeptine degrading bacterial strain, MTHt3, and classified it, based on its 16S rDNA sequence, as a strain of Rhodococcus erythropolis (Nocardiaceae, Actinobacteria). For strain isolation, mixed microbial cultures were obtained from artificially ergot alkaloid-enriched soil, and provided with the ergopeptine ergotamine in mineral medium for enrichment. Individual colonies derived from such mixed cultures were screened for ergotamine degradation by high performance liquid chromatography and fluorescence detection. R. erythropolis MTHt3 converted ergotamine to ergine (lysergic acid amide) and further to lysergic acid, which accumulated as an end product. No other tested R. erythropolis strain degraded ergotamine. R. erythropolis MTHt3 degraded all ergopeptines found in an ergot extract, namely ergotamine, ergovaline, ergocristine, ergocryptine, ergocornine, and ergosine, but the simpler lysergic acid derivatives agroclavine, chanoclavine, and ergometrine were not degraded. Temperature and pH dependence of ergotamine and ergine bioconversion activity was different for the two reactions.ConclusionsDegradation of ergopeptines to ergine is a previously unknown microbial reaction. The reaction end product, lysergic acid, has no or much lower vasoconstrictive activity than ergopeptines. If the genes encoding enzymes for ergopeptine catabolism can be cloned and expressed in recombinant hosts, application of ergopeptine and ergine degrading enzymes for reduction of toxicity of ergot alkaloid-contaminated animal feed may be feasible.

Ergot alkaloids are frequent contaminants of cereal crops. Strategies for their inactivation include the use of microorganisms or enzymes as feed additives capable of degrading ergot alkaloids. Recently, an ergopeptine-degrading Rhodococcus erythropolis strain MTHt3 (DSM 25948) has been isolated from soil and the involved enzymes ErgA and ErgB have been identified. The aim of the current study was to characterise the metabolites formed by degradation of various ergopeptines with the MTHt3 strain, its lysate and the purified enzyme ErgA. Using preparative HPLC, 1H-, 13C- and 2D-NMR as well as HR-MS measurements, two main groups of metabolites formed during microbial and enzymatic degradation of ergopeptines were identified: diketopiperazines (cyclic dipeptides, DKPs) and unstable ergine hydroxy carboxylic acids. However, degradation by strain, lysate and enzyme yielded different end-products. Whereas DKPs were transient and lysergic acid the only final product upon incubation of ergopeptines with the R. erythropolis strain, incubation with the lysate resulted in formation of lysergic acid and two isomeric DKPs at different ratios. Enzymatic degradation by ErgA yielded only one DKP isomer and ended at the stage of the ergine hydroxy carboxylic acids which then spontaneously degraded to ergine. In conclusion, we succeeded in identification of metabolites formed by microbial and enzymatic degradation of ergot alkaloids which is a crucial step in the future development of feed additives for gastro intestinal detoxification of ergopeptines in farm animals.

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